This invention relates to an electrosurgical surgical instrument comprising a handpiece including one or more electrosurgical electrodes. Such instruments are commonly used for the cutting and/or coagulation of tissue in surgical intervention, most commonly in “keyhole” or minimally-invasive surgery, but also in “open” or “laparoscopic assisted” surgery.
It is known to provide an electrosurgical instrument with a cooling system for preventing excess temperatures being developed at the electrode or electrodes. These fall into two categories. The first category includes instruments with a circulating cooling fluid. Examples are U.S. Pat. No. 3,991,764, U.S. Pat. No. 4,202,336, U.S. Pat. No. 5,647,871 and EP 0246350A. It should be noted that, with each of these systems, some or all of the fluid reservoir, pump and fluid supply lines are located externally of the electrosurgical handpiece. The second category includes instruments with heat pipes. Examples are U.S. Pat. No. 6,733,501, U.S. Pat. No. 6,544,264, U.S. Pat. No. 6,503,248, U.S. Pat. No. 6,206,876, and U.S. Pat. No. 6,074,389